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Avascular Necrosis (AVN)
What is avascular necrosis (AVN)?
Avascular necrosis is a bone problem where the blood supply to a bone is damaged or
interrupted, causing damage to the bone. Bones are living tissue, and like all living tissue they
rely on blood vessels to bring blood to keep them healthy. Most living tissues have blood vessels
that come from many directions into the tissue. If one
blood vessel is damaged it may not cause problems,
since there may be a backup blood supply coming in
from a different direction. But certain joints of the body
have only a few blood vessels that bring in blood. One
of these joints is the hip. Damage or interruption of the
blood supply to the hip bone (femoral neck) causes
deterioration of the bone, which can collapse. When
AVN occurs in the hip joint, the top of the femoral head
(the ball portion) collapses and begins to flatten. As the
damage occurs to the bone, it can be painful and cause
difficulty moving the hip. The AVN can cause
significant damage to the bone; often there is healing
over time and the hip becomes pain-free. If the AVN is
more severe, the damage can be more of a problem. AVN can also occur in other bones, and
some people may have it in more than one place.
What causes AVN?
Most of the time, we are not sure of the exact cause of AVN in a patient. However, there are
some risk factors for getting AVN. Anything that damages the blood supply to the hip can cause
AVN. In children and teens with rheumatic diseases, they may be at risk of getting AVN if they
have taken steroids (prednisone). There are other risk factors, for example some people with
lupus have antibodies in their blood which also promote getting blood clots (antiphospholipid
antibodies). People with lupus have inflammation of blood vessels when disease is active, and
this may also be a risk for getting AVN.
How is AVN diagnosed?
AVN is diagnosed by x-ray; if it is in the early stages, xray may be normal and an MRI may need
to be done.
How is AVN treated?
There are no treatments that completely reverse the AVN. When an AVN occurs in the hip,
patients may be told to limit putting weight on the hip for several weeks to prevent further
damage and allow healing. Taking nonsteroidal anti-inflammatory medications or other pain
medications may be necessary to help with the pain. A referral to an orthopedic surgeon is
common; in some cases, there is the possibility of a surgery to try to re-establish blood supply to
the damaged bone and prevent on-going damage. Over time, the injured bone begins to heal
itself; usually the pain settles at that time. However, if there has been a lot of damage to the
bone, orthopedic treatment might be needed later on.
October 2012